Add /diff and /template commands

- /diff command to compare config with backups
  - Shows added/removed/changed files
  - JSON-aware comparison for config files
  - List available backups
- /template command for session templates
  - Built-in templates: daily-standup, code-review, troubleshoot, deploy
  - Each template includes checklist, initial commands, prompt
  - Create custom templates interactively or non-interactively
- Updated shell completions with 21 aliases total
- Test suite now covers 29 tests

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

commands/README.md

@@ -22,6 +22,8 @@ Slash commands for quick actions. User-invoked (type `/command` to trigger).
 | `/workflow` | `/workflows`, `/wf` | List and describe workflows |
 | `/skill-info` | `/skill`, `/skills-info` | Show skill information |
 | `/agent-info` | `/agent`, `/agents` | Show agent information |
+| `/diff` | `/config-diff`, `/compare` | Compare config with backup |
+| `/template` | `/templates`, `/session-template` | Manage session templates |
 | `/maintain` | `/maintenance`, `/admin` | Configuration maintenance |
 | `/programmer` | | Code development tasks |
 | `/gcal` | `/calendar`, `/cal` | Google Calendar access |